A bearing arrangement of, for example, a journal bearing of large turbomachines can include a bearing housing and a bearing shell, an inner side of which is a contact point between rotating and stationary parts.
In order to safeguard a function of a hydrodynamic bearing arrangement during operation and in order to keep friction to a minimum during so-called rotor barring (slow rotation during a cooling down operation), the bearing shell and a bearing section of the rotor should be aligned accurately and parallel with each other.
The mutual aligning can be realized relatively simply by taking measurements during assembly when the bearing housing and a turbine casing are open. If, however, the bearing housing and the turbine casing are closed and bolted together, a deflection line of the turbine casing can be altered. As a result, the bearing housing and bearing shell can be rotated in relation to the rotor and the two components may no longer be parallel to each other. Therefore, the optimum functioning conditions may no longer be fulfilled.
In order to ensure that the bearing shell can be aligned correctly in relation to the rotor, the positions in relation to each other are measured before and after closing the bearing cover and turbine casing. In known methods this has been done by four measuring points at a 12 o'clock position, the measuring being carried out in the radial direction. When the machine is closed, there is no longer access to such measuring points. As a result, information about possible incorrect positioning is hard to determine. It should be added that measuring on a relatively rough (outer wall of the bearing shell) and convex surface (bearing shell, rotor) can be inaccurate. Experience has shown that such measurements are not sufficiently reliable.